This invention relates to a carburetor which can adjust the richness of the mixture to be supplied to the engine at an optimum air-fuel ratio during acceleration.
In improving the driver's comfort and reducing the noxious gas emission from the internal combustion engine of automobiles, it is very important to supply a fuel mixture of optimum air-fuel ratio under any driving condition.
Conventional carburetors employ an acceleration device for correcting the air-fuel ratio at a time of acceleration. However, the conventional device cannot meet the recent higher standards for noxious gas emission.
FIG. 1 shows the conventional carburetor with an acceleration device. Fuel is contained in an acceleration fuel reservoir 2 as well as in a fuel chamber 1. When a driver depresses an accelerator pedal to accelerate the engine, an acceleration lever 5 is rotated about the fulcrum 6 by the link 4 connected with the throttle valve 3 and pushes the piston 7 downwardly with the result that the fuel in the acceleration fuel reservoir 2 is delivered through the passage 8 and ejected from the nozzle 9 into the mixture. Ball valves 10 and 11 are provided at the inlet and outlet of the acceleration fuel reservoir 2 and which serve to prevent the fuel backflow. A venturi 12, a nozzle 13, and a float 14 are included. With this kind of acceleration device it is impossible to provide the mixture of optimum richness at all times under various accelerating conditions. Namely, in this conventional carburetor, the mixture is rendered rich momentarily only in the period in which the piston 7 is depressed as a result of a depression of the accelerator pedal, and the initial condition recovers soon to render the mixture unnecessarily lean. Thus, the conventional carburetor needs to be improved for better acceleration and reduced noxious emission from the engine.